The invention relates to a battery-charging device for an electric vehicle and, more particularly, to a battery-charging device, for an electric vehicle having a contact element arranged on the vehicle side and a stationary charging station having a contact element which can be made to automatically make contact with the contact element on the vehicle side at a specific height above the ground as a result of the approaching movement of the vehicle.
German Patent document DE-A 29 29 067 A1 discloses a known battery-charging device. The contact elements are designed in the known device on the vehicle front side or on the charging-station side in such a manner that they are pressed against one another for the purpose of making charge contact by driving the vehicle up to the charging station. In this manner, no separate actuating means are necessary for making contact with the contact elements.
For this purpose, track rails are arranged in front of the stationary charging station. The track rails are downwardly inclined in the direction of the charging station and form a positive guide for an arriving electric vehicle. In the charging position, the vehicle is therefore located on an oblique plane with the front side being downwardly inclined. As a result, the contact elements arranged on the vehicle front side remain pressed against the contact elements fitted to the charging station at a corresponding height. To ensure that reliable contact is made even in the event of noticeable differences in height, e.g. in the case of different vehicle loading states, the contact elements which lie against each other are designed in this location as contact rails. The rails run in a manner intersecting each other. Alternatively, a contact element is designed as a contact pin and the complementary contact element is as a contact plate which slides thereon. In each case, two interacting pairs of contact elements are arranged at a horizontal distance from one another.
A further known battery-charging device is disclosed in Great Britain Patent document GB 1 282 974. The stationary charging station comprises two supporting posts, to which a holder is screwed for two charging contact pins. The contact pins are horizontally displaceable on the holder above C-members. The holder, for its part, can be manually adjusted in terms of height by releasing the screw connections, adjusting the holder along slotted guides in the support posts, and again fastening the screw connections. In this manner, the contact pins can be manually set to a height position which is suitable for a respective electric vehicle. The contact pins engage automatically into two contact slots, fitted on the front side of the vehicle at a horizontal distance, for the purpose of making contact when the vehicle approaches the charging station.
For the purpose of automating the charging operation to a large extent, communications are provided in the case of newer battery-charging devices between a control unit on the vehicle side and a control unit on the charging-station side. The control units often also include computers. So, for example, in a known battery-charging device disclosed in Laid-open Great Britain Patent document GB 2 185 866 A, a control computer on the vehicle side communicates with a control computer on the charging-station side via an RS232 interface or an inductive coupling. In a further battery-charging device of this kind, shown in U.S. Pat. No. 5,049,802, the control on the vehicle side communicates via radio contact with a control unit on the charging-station side which controls the charging operation. In this case, data is conveyed by the control unit on the vehicle side by radio contact. The data contain, inter alia, an item of information about the fact that the vehicle is connected, ready to be charged, to the charging station as well as concerning the instantaneous charging state of the battery so that the charging operation can be set in a corresponding manner by the charge control unit.
Radio communication between a charging station and an electric vehicle is also provided in the case of a data-collecting arrangement for a battery-driven vehicle as disclosed in German Patent document DE-A 39 02 339 A1. Vehicle-specific and/or battery-specific data that has been collected on the vehicle side can be transmitted to an evaluation unit in the charging station. The evaluation unit evaluates the received data for the purpose of controlling the charging operation.
There is therefore needed a battery-charging device of the above-mentioned type, which allows vehicles having different loads, or of different vehicle types, to be automatically coupled in a simple and reliable manner to a stationary charging station. The battery-charging device should allow a reliable, automatic charging operation.
These needs are met according to the present invention by a battery-charging device for an electric vehicle having a contact element arranged on the vehicle side and a stationary charging station having a contact element which can be made to automatically make contact with the contact element on the vehicle side at a specific height above the ground as a result of the approaching movement of the vehicle. A transmitter is provided for transmitting data which contains an item of information about the instantaneous height position of the contact element on the vehicle side. The charging station contains a receiver for the data transmitted by the transmitter, a charge control unit connected to the receiver, as well as a height adjustment device. The height adjustment device can be driven by the charge control unit for the contact element on the station side.
It is an advantage of the present invention that it is possible to detect on the vehicle side the instantaneous height position of the vehicle side contact element which changes, for example, due to different loading states for the same vehicle, or which can also be different for different types of vehicles even in the empty state. The height position can be transmitted as an item of information to the charging station whose charge control unit evaluates this item of information and undertakes a matching adjustment in terms of height for the contact element on the station side. Thus, the interacting contact elements are located at a mutually matching level when the vehicle approaches the charging station and contact can be made automatically as a result of driving up to the charging station.
An advantageous embodiment of the invention provides a cover to protect the busbars against soil, humidity and unauthorized touching when no vehicle battery to be charged is connected. In order for the automatic coupling of the vehicle to the charging station to remain nevertheless possible, the cover can be moved, via control by the charge control unit, into a corresponding release position.
As a result of a further advantageous embodiment of the invention, contact is made and, thus, a charging current flows only when the contact peg is completely inserted into the associated contact rail and that a relatively large contact surface is available.
If the charging operation is carried out, as usual, using two contact connections, then it is a further advantage to provide a rubber buffer, provided between the contact rails, for protecting rear charging station parts from being damaged when the vehicle is coupled and, additionally, contributing to the protection from being touched since the rubber buffer prevents the two busbars from being touched at the same time.
In a preferred embodiment, the battery-charging device has a control device on the vehicle side for controlling the transmitter. In a further development of this embodiment, the control device on the vehicle side preferably detects the data which the charge control unit requires for controlling a desired charging operation, e.g. data about an imminent charging operation and/or about the type of battery and/or about the charging state of the battery. The control unit on the vehicle side passes this data on to the transmitter for transmission to the charging station. Furthermore, the control device on the vehicle side can be used for driving the contact element on the vehicle side when this is arranged between a charging position and a quiescent position in a manner so as to be movable on the vehicle. The contact element is directed into the charging position by the control device after a user request has been received for charging the battery.
It is a further advantage of the present invention that a level matching can be achieved in an advantageous manner in the case of changes of the vehicle loading state during a battery charging operation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.